1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to an electromagnetic micro actuator and a method of manufacturing the electromagnetic micro actuator.
2. Description of the Related Art
A scanner, which is used in a large-sized display device, such as a micro actuator for deflecting a laser beam using an electromagnetic force or effect, typically includes at least one permanent magnet, a moving plate, and a mirror provided on the moving plate to change an optical path. The moving plate includes a coil part receiving a current. As an electric force generated by a current applied to the coil part interacts with a magnetic force generated by the permanent magnets, the moving plate is rotated. Thus, the angle of the mirror can be adjusted using this rotation of the moving plate. For this reason, the scanner using the electromagnetic effect includes the coil part that receives a current. Such a coil part formed in a substrate is shown in FIGS. 1A and 1B.
FIGS. 1A and 1B are cross-sectional views illustrating a coil part 40 formed in a substrate 20.
Referring to FIG. 1A, a metal layer 30 is formed on the substrate 20, and the coil part 40 is formed on the metal layer 30 and includes a plurality of coil sections 41 spaced a predetermined distance from each other. Referring to FIG. 1B, the coil part 40 with the coil sections 41 is disposed in the substrate 20 to a predetermined depth from an upper side of the substrate 20. The substrate 20 is formed of Si and the coil part 40 is formed of a high thermal conductivity metal.
FIG. 2 is a view illustrating a substrate 20 which is deformed by thermal expansion when a current is applied to a coil part 41. Referring to FIG. 2, as a current is applied to the coil 41, heat is generated, deforming the coil 41. The deformation of the coil 41 affects the substrate 20, causing the substrate 20 to deform by δ in its longitudinal direction. The thermal expansion coefficient of Si forming the substrate 20 is smaller than that of Cu forming the coil 41. Therefore, when heat is generated by a current applied to a coil part 40 formed of the coil sections 41, the deformation of the Si forming the substrate 20 is negligible since the Si is not sensitive to heat. However, the thermal expansion of the Cu of the coil part 40 is not negligible, thereby causing the deformation of the substrate 20. When the substrate 20 is deformed, a mirror connected to the substrate 20 is also affected. Therefore, the optical characteristics and structural reliabilities of the micro and other optical components are deteriorated.